In concentrating maple syrup, it is necessary to boil off the water which forms a high percentage of the liquid content of the maple sap thereby concentrating the maple syrup by subjecting the sap as removed from the maple tree to heat, and permitting the water vapor to be driven therefrom. Typically, the maple sap is fed into an upwardly open flue pan supported over a wood or coal fire and collecting the concentrated maple syrup which fails to be driven off by the vaporization process. Such known maple syrup evaporator apparatus is relatively ineffective. There is considerable waste heat generated and the steam driven off by the process of heat application to the sap filling the flue pan to a given level is simply lost.
It is therefore a primary object of the present invention to provide a piggy back evaporator physically mounted in overlying position to an evaporator flue pan, to feed maple sap to both the flue pan and a piggy back pan, to utilize the heat within the steam generated by vaporization of the water content of the maple sap within the flue pan as the source of heat for the piggy back pan while, simultaneously increasing the heat exchange between the steam and the sap born by the piggy back pan.